The Restoration Potential of Small Channelized Streams Assessed Through Hydrological and Hydrogeological Dynamics
Abstract
Stream channelization for agricultural purposes hampers several ecological functions provided by the channel-floodplain environment. Indeed, many local-to-catchment scale ecological problems are directly correlated to the drastic modifications of the river systems, limiting floodplain connectivity in these small agricultural channelized streams. A key component to the rehabilitation of ecological functions in such environments, including those provided by riparian wetlands, is to restore hydrological connections with former meander oxbows. However, a thorough understanding of the level of connectivity between the channelized stream and the artificially abandoned meander bend is needed to determine the best restoration approach (passive vs active for instance) and which sites to prioritise. This research project, funded by the Canadian National Wetland Conservation Fund, proposes an eco-hydraulic approach to assess the potential for wetland restoration in small agricultural channelized streams in the St. Lawrence Lowland setting of southern Quebec (Canada). As a first step, spatio-temporal variability of surface water-groundwater interactions between straightened reaches and former meanders is investigated through a dense network of piezometers at three sites exhibiting a diversity of unconsolidated sediments. High-resolution eco-geomorphological analyses in the channel and within the ancient floodplain are combined for fluvial habitats quality assessment. Former oxbows formed of fine to very-fine grained alluvial sediments contrast with adjacent regional deposits in terms of magnitude and frequency of hydraulic gradient fluctuations and storage capacity, especially outside flooding season. These preliminary results highlight the importance of former oxbows in stream baseflow from channelized streams and the potential of rehabilitating riparian wetland habitats at these sites. Qualitative and quantitative criteria for selecting the sites and method of restoration are proposed based on experimental analysis and are tested through conceptual hydrogeological modelling. This multi-disciplinary research project will contribute to a knowledge-based method for assessing the restoration potential of channelized streams based on connectivity with former meanders.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H23K2085B
- Keywords:
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- 0408 Benthic processes;
- BIOGEOSCIENCESDE: 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 1806 Chemistry of fresh water;
- HYDROLOGYDE: 1830 Groundwater/surface water interaction;
- HYDROLOGY